1. Field of the Invention
The present invention relates to an ophthalmic medical device and more prticularly, to an apparatus for diagnosing diseases through non-invasive measurement of the eye fundus.
2. Description of the Prior Art
Considerable advances have occurred in the practice of ophthalmic medicine in recent years, for example, laser treatment of the retina of an eye has become common. To assist the ophthalmic medical profession in examining a patient's eye and diagnosing various diseases, various forms of eye fundus cameras have been utilized. One of the causes of loss of human eyesight is diabetic retinopathy. This diabetic condition affects the small eye blood vessels by increasing their size. Frequently, these blood vessels will break due to their fragility and will result in a destruction of the optic rod and cone receptors of the retina resulting from a lack of nutrition by blood flow. When this disease has been properly diagnosed, the medical profession has been able to retard the loss of eyesight by burning or searing closed the specific enlarged blood vessels with the use of a laser. The localized loss of receptors in the burnt area does not reduce the overall vision.
The conventional manner in which a diabetic retionopathy is diagnosed is by use of an eye fundus camera. The doctor aligns the patient with his chin on a headrest and centers the camera optics relative to the patient's eye. Frequently, flash illumination is utilized for taking photographs. The doctor subsequently makes his diagnostic decision by observing the photographs taken of the eye fundus. This diagnosis, however, depends greatly on the personal ability and experience of the doctor. Accordingly, a reliable diagnosis is only possible by a highly skilled doctor and the subjective possibility of the wrong diagnosis is an inherent problem.
U.S. Pat. Nos. 4,068,932, 3,936,844, 3,925,793 and 3,016,000, plus French Pat. No. 1,127,947 (1956) are cited of general interest to disclose various eye fundus cameras. U.S. Pat. No. 3,948,248 is cited of general interest to disclose a central transmission of ultrasonic energy with a concentric pickup device surrounding the oscillating transducer.
Finally, U.S. Pat. No. 4,157,708 is cited of general interest to disclose the obtaining of a final plethysmograph that is free from any noise resulting from eye cornea reflection as a result of a subtractive processing of a first and second output signal from different wavelengths.
The ophthalmic medical profession is still seeking an optimum medical apparatus to diagnose diseases from measurements of the eye fundus.